Tory leader Kemi Badenoch has warned Labour's Brexit civil war would be a "disaster" for the UK.
Mrs Badenoch, who voted for the UK to leave the European Union in 2016, issued her warning following negotiations with Mauritius over the Chagos Islands and France on a "one-in, one-out" migrant deal.
She claimed both accords proved Labour was unable to negotiate in the interests of the British people, sparking fears of a sell-out to Brussels.
Mrs Badenoch told The Daily Mail: "What we see before us is a timid and tired Labour Party, exhausted after less than two years in Government.
"Does anyone believe these clowns can negotiate with the EU?
"They're terrified of making any difficult decisions and will only end up giving away power and money just like they did with their terrible Chagos deal and the failed one-in, one-out deal with France."
She added: "It will be a disaster for the country and they will reap the whirlwind if they plunge us back into the Brexit wars, ignoring the clear message the country sent in the referendum of 2016 and the elections of 2017 and 2019 – Get Brexit Done."
Lord Gove, who was a leading architect of the Vote Leave campaign, also warned: "The drive towards rejoining is not just acceleration into an economic cul-de-sac, it is also a betrayal of the democratic vote which politicians promised would be honoured and respected."
The fiery Brexit row was sparked by ex-Health Secretary Wes Streeting declaring his support for the UK rejoining the EU.
Launching his leadership bid, Mr Streeting said: "We need a new special relationship with the EU, because Britain’s future lies with Europe and one day, one day, back in the European Union.”
Greater Manchester Mayor Andy Burnham, whose allies accused Mr Streeting of sabotage, is watering down his previous calls to rejoin the Brussels bloc.
Speaking on the campaign trail in Makerfield, Mr Burnham said: “I’ve said in the long-term there is a case for that, but I'm not advocating that in this by-election.”
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David Lammy refuses to say whether he wanted to rejoin the EU
David Lammy has refused to say whether he wanted to rejoin the EU
|PA
David Lammy has refused to say whether he wanted to rejoin the EU.
The Deputy Prime Minister insisted the Government is "absolutely committed" to its manifesto red lines.
he told Sky News: "We set red lines in the manifesto that we are absolutely committed to.
"I see now that there’s a debate about the next election. I’m not going to make a commitment about the next election and the next manifesto.”
Asked whether he would personally like to rejoin, he said: "I’m committed to collective responsibility. The manifesto we stood on. Wes Streeting has left the Government, he can have a debate, he can comment, that is not my position."
He added: "I think we should remember that we are in Government and the British people won’t thank us for debates and comments, they want delivery.
"Delivery is what they want to see."
Keir Starmer will not be setting out a timetable for his departure, claims David Lammy
Sir Keir Starmer will not be setting out a timetable for his departure, David Lammy has claimed.
The Deputy Prime Minister said: "Let me be really clear, Keir Starmer remains the most resilient person I know in my life.
"I spoke to him twice yesterday. He has a strength of character, a fighting experience. There will be no timetables. What there is is getting on with the business of Government.
"We’re really crystal clear about that. At the moment there is no contest. What there is is his determination to deliver for the British people, accelerate the pace over the coming months."
He added: "There will be no timetable for departure."
Asked whether he would be campaigning for Andy Burnham in the Makerfield by-election, the Deputy Prime Minister said he would be “100 per cent".
He told Sky News: "This is a Labour by-election. We’ve got quite threatened votes, Reform will be challenging hard.
"I’ve known Andy Burnham for over a quarter of a century. We were both proteges of the wonderful Tessa Jowell.
"We worked together all those years ago under Tony Blair. He will be a great addition to parliament for Makerfield. He has my full support.
"I will be up there, much of the Cabinet will be up there of course, the Labour movement will be up there to make sure we win."
Tory Shadow Minister says the Conservatives will stand in the Mayfield By-election
Matt Vickers has confirmed that the Conservatives will stand in the Mayfield By-election.
He told GB News: "Kemi's been really clear. There will be no deals. There will be no stitch-ups.
"The electorate in Makerfield will get the right to make that decision.
"If they want to vote for a party that is serious about reducing welfare, that's serious about bringing back the two-child cap, that's serious about scrapping stamp duty and about axing business rates for small businesses across the country.
"That choice is going to be on the ballot paper.
"That choice is the Conservative Party, and people will have the opportunity to have their say on it."
Matt Vickers: 'Labour is desperate to distract from the trashing it's made of our economy'
Matt Vickers has claimed Labour are trying to distract the public from the issues facing Britain
|GB NEWS
The Shadow Minister of State for Illegal Immigration, Crime, Policing and Fire has claimed Labour are trying to distract the public from the issues facing Britain when questioned on Labour's leadership rumours.
The MP for Stockton West said: "This is a Government that is desperate to distract from the trashing it's made of our economy."
He added: "It's because of the jobs tax, because the increases in national insurance, because the increases in business rates that are slamming businesses on high streets throughout the country.
"It's because of the employment rates bill and everything else that's coming down the line, it's because our energy prices are amongst the highest on the planet.
"That's what's doing these businesses in decisions made in No10 Downing Street that have real consequences.
"It's no surprise that the Labour Party wants to talk about anything but that economic carnage that they've caused."
'A gift for Farage!' Labour's reverse Brexit row sparks bitter spat between Andy Burnham and Wes Streeting
Andy Burnham's allies have accused Labour leadership rival Wes Streeting of deliberately trying to undermine the Greater Manchester Mayor's Makerfield by-election campaign.
Mr Streeting, who threw his weight behind Mr Burnham contesting the Brexit-backing seat, appeared to put his soon-to-be opponent in a difficult position after setting out a path for the UK to rejoin the European Union.
Speaking at an event in London on Saturday, the ex-Health Secretary said: “Britain’s future lies with Europe, and one day back in the European Union.”
Mr Burnham, who expressed a similar view last year's Labour Party conference, is offering a somewhat different message to voters in Makerfield.
However, Labour insiders fear a row over Brexit is now a gift to Reform UK in Makerfield.
A senior source told The Times: “I despair. It’s like a gift to Farage. What Wes did reeks of desperation and selfishness.”
An ally of Mr Burnham added: “Wes’s only hope at becoming the next leader is for Andy to lose the by-election. [Mr Streeting’s] comments … are counterproductive to Labour winning this by-election."
Labour Brexit civil war erupts as Lisa Nandy launches scathing attack on Wes Streeting's plea to rejoin EU
Lisa Nandy appeared to have opened the door to a Labour civil war on Brexit as she accused Wes Streeting of a “fundamental misreading” of the public mood.
Announcing his intentions to challenge Keir Starmer for the leadership yesterday, the former Health Secretary called for the UK to rejoin the EU 10 years after the referendum.
Reacting to the speech of GB News, Ms Nandy described her colleague’s stance as “a bit odd” in the wake of their party’s local election drubbing by Nigel Farage’s Reform UK and Zack Polanski's Greens.
“We got an absolute kicking at the poles, and it hurt, and it still hurts,” she told Camilla Tominey.
“To respond to that with re-entering the European Union seems to me to be a fundamental misreading of what people are asking us for,” the Culture Secretary said.
“If going back into the EU was the answer to the problems that people have in their lives, then we would be telling people in towns like mine that everything was fine in 2015. It absolutely wasn't."
Wes Streeting's push to rejoin EU and Andy Burnham's U-turn
The fiery Brexit row was sparked by ex-Health Secretary Wes Streeting declaring his support for the UK rejoining the EU.
Launching his leadership bid, Mr Streeting said: "We need a new special relationship with the EU, because Britain’s future lies with Europe and one day, one day, back in the European Union.”
Greater Manchester Mayor Andy Burnham, whose allies accused Mr Streeting of sabotage, is watering down his previous calls to rejoin the Brussels bloc.
Speaking on the campaign trail in Makerfield, Mr Burnham said: “I’ve said in the long-term there is a case for that, but I'm not advocating that in this by-election.”